In deep water sport fishing a heavy weight is employed at the end of a downrigger cable and a connection device is provided to hold the fishing line to the downrigger at a desired deep level in the water. A release device is required to free the fishing line from the downrigger line when a strike occurs. In the prior art these devices have generally been mechanically complicated or magnetic. Some of the devices have been subject to corrosion, others either failed to release or release too easily. Where the devices hold the fishing line too securely, there is a tendency to break the line when a strike occurs and this requires the use of excessively heavy lines to avoid their breakage.
A search of the patent literature disclosed a number of devices for releasing the line when a strike occurs. For example, U.S. Pat. No. 4,012,863 to Lori shows a relatively complicated releasable device and also one that appears to be subject to be released too easily from the downrigger.
The following patents, found in the search, are of general interest:
U.S. Pat. No. 2,545,185 Winslow PA1 U.S. Pat. No. 2,562,054 Mathieu PA1 U.S. Pat. No. 2,687,592 Purcell PA1 U.S. Pat. No. 2,830,400 Perry PA1 U.S. Pat. No. 3,229,408 Kohfield PA1 U.S. Pat. No. 3,614,700 Harrison PA1 U.S. Pat. No. 3,628,274 Wojahn PA1 U.S. Pat. No. 3,861,074 Wood PA1 U.S. Pat. No. 3,925,920 Walker PA1 U.S. Pat. No. 3,930,330 Black PA1 U.S. Pat. No. 3,939,595 Lockett PA1 U.S. Pat. No. 3,974,589 Henze et al. PA1 U.S. Pat. No. 4,065,869 Berry PA1 U.S. Pat. No. 4,212,127 Daniels.